CN114120922A

CN114120922A - Display device and electronic device comprising same

Info

Publication number: CN114120922A
Application number: CN202110806552.1A
Authority: CN
Inventors: 劉承振; 洪賢基
Original assignee: LG Display Co Ltd
Current assignee: LG Display Co Ltd
Priority date: 2020-08-25
Filing date: 2021-07-16
Publication date: 2022-03-01
Anticipated expiration: 2041-07-16
Also published as: US20220068219A1; US20230079387A1; US11574602B2; CN114120922B; US11893945B2; KR20220026311A

Abstract

The present disclosure discloses a display device and an electronic device including the same. The display device includes: a first data line group including first data lines connected to pixels arranged at a first resolution; a second data line group including a second data line connected to the pixels arranged at the first resolution and the pixels arranged at the second resolution; a first gamma compensation voltage generating unit dividing a first reference voltage and outputting a first gamma compensation voltage; a second gamma compensation voltage generating unit dividing a second reference voltage and outputting a second gamma compensation voltage; a first data driving unit converting the first pixel data into first gamma compensation voltages output from the first gamma compensation voltage generating unit and outputting the first data voltages to the first data line group; and a second data driving unit converting the second pixel data into a second gamma compensation voltage output from the second gamma compensation voltage generating unit and outputting the second data voltage to the second data line group.

Description

Display device and electronic device comprising same

Cross Reference to Related Applications

This application claims priority and benefit from korean patent application No. 10-2020-0107184, filed on 25/8/2020, the entire disclosure of which is incorporated herein by reference.

Technical Field

The present disclosure relates to a display device and an electronic device including the same.

Background

Electroluminescent display devices are roughly classified into inorganic light emitting display devices and organic light emitting display devices according to the material of a light emitting layer. The active matrix type organic light emitting display device includes a self-luminous organic light emitting diode (hereinafter, referred to as "OLED"), and advantageously has high response speed, high light emitting efficiency, high luminance, and a wide viewing angle. In the organic light emitting display device, an OLED is formed in each pixel. Since the black gray scale can be expressed as full black, the organic light emitting display device has a high response speed, excellent light emitting efficiency, excellent luminance, excellent viewing angle, and excellent contrast and color reproducibility.

Multimedia functions of mobile devices are being improved. For example, a camera is basically built in a smartphone, and the resolution of the camera tends to increase to the level of a conventional digital camera. However, the front camera of the smartphone restricts the screen design, making the screen design difficult. To reduce the space occupied by the camera, screen designs including notches or perforations have been employed in smartphones. However, the screen size is still limited due to the camera, and therefore full-screen display cannot be achieved.

In order to realize full-screen display, the following methods have been proposed: a sensing region is provided in which low-resolution pixels are arranged in a screen of a display panel, and a camera is arranged below the display panel at a position facing the sensing region. The sensing area in the screen is used as a transparent display for displaying images. Such a sensing region has low transmittance and low brightness due to the pixels.

Optical compensation is required for each region to improve the luminance difference and the color difference between the low-resolution pixel and the high-resolution pixel. The optical compensation for each region is fixed analog gamma and corrected with digital gamma. The analog gamma should be set to be high based on the sensing region requiring a high driving voltage, but a loss of an actual driving data bit in the display region may occur. There is a need for a method capable of gamma correction in all regions using only analog gamma.

Disclosure of Invention

The present disclosure is directed to addressing all of the above-mentioned needs and problems.

The present disclosure provides a display device that may uniformize image quality of a full-screen display having a sensing region, and an electronic device including the same.

It should be noted that the object of the present disclosure is not limited to the above object, and other objects of the present disclosure will be apparent to those skilled in the art from the following description.

The display device according to the present disclosure includes: a first data line group including first data lines connected to pixels arranged at a first resolution in a first region of a screen; a second data line group including second data lines connected to pixels arranged at a first resolution and pixels arranged at a second resolution lower than the first resolution in a second region of the screen; a first gamma compensation voltage generating unit dividing a first reference voltage and outputting a first gamma compensation voltage; a second gamma compensation voltage generating unit dividing a second reference voltage and outputting second gamma compensation voltages different according to respective resolutions; a first data driving unit converting first pixel data to be written in the pixels of the first region into first gamma compensation voltages output from the first gamma compensation voltage generating unit and outputting the first data voltages to first data lines of the first data line group; and a second data driving unit converting second pixel data to be written in the pixels of the second region into the first gamma compensation voltage output from the second gamma compensation voltage generating unit and outputting the first data voltage to the second data line of the second data line group. According to the present disclosure, the image quality of a full-screen display having a sensing region may be uniformized.

According to the present disclosure, a separate analog gamma reference voltage may be set in the sensing region, and thus, all regions may be driven without losing data bits.

According to the present disclosure, since the analog gamma reference signal in the boundary portion between the display region and the sensing region varies according to the scan time, the boundary portion can be further compensated.

Drawings

The above and other objects, features and advantages of the present disclosure will become more apparent to those of ordinary skill in the art by describing in detail exemplary embodiments thereof with reference to the attached drawings, in which:

fig. 1 is a cross-sectional view schematically showing a display panel according to an embodiment of the present disclosure;

fig. 2 is a diagram showing an example of the arrangement of pixels in the Display Area (DA);

fig. 3 is a diagram showing an example of pixels and light-transmitting portions in the first sensing region (CA);

fig. 4 is a diagram showing an overall configuration of a display device according to an embodiment of the present disclosure;

fig. 5 is a diagram schematically showing the configuration of a driving Integrated Circuit (IC) shown in fig. 4;

fig. 6 and 7 are circuit diagrams showing examples of a pixel circuit to which an internal compensation circuit is applied;

fig. 8 is a diagram illustrating a driving method of the pixel circuit shown in fig. 6 and 7;

fig. 9 to 12H are diagrams showing examples in which the gamma reference voltage varies according to each region of the display panel;

fig. 13A and 13B are diagrams showing a configuration of a driving IC applied to a mobile device;

fig. 14A and 14B are diagrams showing a configuration of a driving IC applied to a display device;

fig. 15 is a block diagram schematically showing a configuration of a data driving unit according to an embodiment;

fig. 16 is a diagram showing a display device to which a fingerprint recognition module is applied according to an embodiment;

fig. 17 is a diagram showing an example of pixels and photosensors in the second sensing region SA;

fig. 18A and 18B are diagrams illustrating an operation of the second sensing region illustrated in fig. 17; and

fig. 19 is a diagram showing a display device to which both a camera module and a fingerprint recognition module are applied according to an embodiment.

Detailed Description

Advantages and features of the present disclosure and methods for accomplishing the same will become more apparent from the following description of embodiments taken in conjunction with the accompanying drawings. However, the present disclosure is not limited to the following embodiments, but may be implemented in various different forms. Rather, the present embodiments will complete the disclosure of the present disclosure and will fully convey the scope of the disclosure to those skilled in the art. The present disclosure is to be limited only by the scope of the following claims.

Shapes, sizes, ratios, angles, numbers, and the like, which are shown in the drawings to describe embodiments of the present disclosure, are merely examples, and the present disclosure is not limited thereto. Like reference numerals generally refer to like elements throughout the specification. Further, in describing the present disclosure, detailed descriptions of known related art may be omitted to avoid unnecessarily obscuring the subject matter of the present disclosure.

Terms such as "comprising," including, "" having, "and" consisting of, "as used herein, are generally intended to allow for the addition of other components, unless the term is used in conjunction with the term" only. Any reference to the singular may include the plural unless explicitly stated otherwise.

Components are to be construed as including a general range of error even if not explicitly stated.

When terms such as "upper", "above", "lower" and "near" are used to describe a positional relationship between two components, one or more components may be located between the two components unless the terms are used with the terms "immediately" or "directly".

The terms "first," "second," and the like may be used to distinguish one element from another, but the function or structure of an element is not limited by the number of preceding elements or the name of the element.

The following embodiments may be partially or wholly combined or combined with each other, and may be technically associated and operated in various ways. Embodiments may be implemented independently of each other or in association with each other.

Hereinafter, various embodiments of the present disclosure will be described in detail with reference to the accompanying drawings.

In the embodiment, a novel scheme is proposed in which a screen is divided into a first region including pixels arranged at a first resolution and a second region including pixels arranged at the first resolution and pixels arranged at a second resolution lower than the first resolution, a first gamma compensation voltage generated by dividing a first reference voltage is applied to the first region, and a different second gamma compensation voltage generated by dividing a first voltage level and a second voltage level of a second reference voltage according to the respective resolutions is applied to the second region.

In this case, when the first resolution is referred to as high resolution and the second resolution is referred to as low resolution, a region where pixels are arranged at low resolution is referred to as a sensing region. Here, the sensing region includes at least one of a first sensing region having a camera module and a second sensing region having a fingerprint recognition module, but the present disclosure is not limited thereto. Such a sensing region is a region designed to have a resolution lower than that of the display region.

Fig. 1 is a cross-sectional view schematically showing a display panel according to an embodiment of the present disclosure, fig. 2 is a view showing an example of a pixel arrangement in a display area DA, and fig. 3 is a view showing an example of a pixel and a light-transmitting portion in a first sensing area CA. In fig. 2 and 3, wirings connected to the pixels are omitted.

Referring to fig. 1 and 2, the screen of the display panel 100 includes at least a display area DA in which pixels are arranged at a high resolution and a first sensing area CA in which pixels are arranged at a low resolution, and is divided into a first area 110a including pixels arranged at a high resolution and a second area 110b including pixels arranged at a high resolution and pixels arranged at a low resolution (as shown in fig. 9). Here, the region where the pixels are arranged at the high resolution (i.e., the high resolution region) may include a region where the pixels are arranged at a high number of Pixels Per Inch (PPI) (i.e., the high PPI region), and the region where the pixels are arranged at the low resolution (i.e., the low resolution region) may include a region where the pixels are arranged at a low PPI (i.e., the low PPI region).

The display area DA and the first sensing area include a pixel array in which pixels to which pixel data is written are arranged. The number of pixels per unit area (i.e., PPI) of the first sensing region CA is lower than the PPI of the display region DA to ensure the transmittance of the first sensing region CA.

The pixel array of the display area DA includes a pixel area (first pixel area) in which a plurality of pixels having a high PPI are arranged. The pixel array of the first sensing region CA includes a pixel region (second pixel region) in which a plurality of pixel groups PG separated by a light-transmitting portion and thus having a relatively low PPI are arranged. In the first sensing area CA, external light may pass through the display panel 100 through a light-transmitting portion having high light transmittance, and may be received by an imaging element module below the display panel 100.

Since the display area DA and the first sensing area CA include pixels, an input image is reproduced on the display area DA and the first sensing area CA.

Each pixel of the display area DA and the first sensing area CA includes sub-pixels having different colors to realize colors of an image. The sub-pixels include a red sub-pixel (hereinafter, referred to as "R sub-pixel"), a green sub-pixel (hereinafter, referred to as "G sub-pixel"), and a blue sub-pixel (hereinafter, referred to as "B sub-pixel"). Although not shown, each pixel P may further include a white sub-pixel (hereinafter, referred to as "W sub-pixel"). Each sub-pixel may include a pixel circuit and a light emitting element OLED.

The first sensing area CA includes pixels and an imaging element module disposed under the screen of the display panel 100. The lens 30 of the imaging element module displays an input image by writing pixel data of the input image into the pixels of the first sensing area CA in the display mode. The imaging element module takes an external image in an imaging mode and outputs picture or moving image data. The lens 30 of the imaging element module faces the first sensing area CA. External light is incident on the lens 30 of the imaging element module, and the lens 30 collects the light in the image sensor omitted in the drawing. The imaging element module takes an external image in an imaging mode and outputs picture or moving image data.

In order to ensure the transmittance, since the pixels are removed from the first sensing area CA, an image quality compensation algorithm for compensating the luminance and color coordinates of the pixels in the first sensing area CA may be applied.

In the present disclosure, since the low-resolution pixels are arranged in the first sensing area CA, the display area of the screen is not limited with respect to the imaging element module, and thus full-screen display can be achieved.

The display panel 100 has a width in the X-axis direction, a length in the Y-axis direction, and a thickness in the Z-axis direction. The display panel 100 includes a circuit layer 12 disposed on a substrate 10 and a light emitting element layer 14 disposed on the circuit layer 12. A polarizing plate 18 may be disposed on the light emitting element layer 14, and a cover glass 20 may be disposed on the polarizing plate 18.

The circuit layer 12 may include a pixel circuit connected to a wiring such as a data line, a gate line, and a power supply line, a gate driving portion connected to the gate line, and the like. The circuit layer 12 may include circuit elements such as transistors and capacitors implemented as Thin Film Transistors (TFTs). The wiring and circuit elements of the circuit layer 12 may be formed of a plurality of insulating layers, two or more metal layers separated by an insulating layer therebetween, and an active layer including a semiconductor material.

The light emitting element layer 14 may include light emitting elements driven by pixel circuits. The light emitting element may be implemented as an Organic Light Emitting Diode (OLED). The OLED includes an organic compound layer formed between an anode and a cathode. The organic compound layer may include a hole injection layer HIL, a hole transport layer HTL, an emission layer EML, an electron transport layer ETL, and an electron injection layer EIL, but the disclosure is not limited thereto. When a voltage is applied to the anode and the cathode of the OLED, holes passing through the hole transport layer HTL and electrons passing through the electron transport layer ETL move to the light emitting layer EML to form excitons, thereby emitting visible light from the light emitting layer EML. The light emitting element layer 14 may be disposed on pixels that selectively transmit light having wavelengths of red, green, and blue, and may further include a color filter array.

The light-emitting element layer 14 may be covered with a protective film, and the protective film may be covered with an encapsulation layer. The protective layer and the encapsulation layer may have a structure in which organic films and inorganic films are alternately stacked. The inorganic film prevents permeation of moisture or oxygen. The organic film planarizes the surface of the inorganic film. When the organic film and the inorganic film are laminated in multiple layers, the movement path of moisture or oxygen is longer than that of a single layer, and thus the permeation of moisture/oxygen affecting the light-emitting element layer 14 is effectively blocked.

Polarizer plate 18 may be adhered to the encapsulation layer. The polarizing plate 18 improves outdoor visibility of the display device. The polarizing plate 18 reduces the amount of light reflected from the surface of the display panel 100, blocks light reflected from the metal of the circuit layer 12, and thus improves the brightness of the pixel. The polarizing plate 18 may be implemented as a linear polarizing plate and a polarizing plate in which a phase retardation film is combined with each other, or a circular polarizing plate.

In the display panel of the present disclosure, each pixel region of the display region DA and the first sensing region CA includes a light shielding layer. The light shielding layer is removed from the light-transmitting portion of the first sensing region to define the light-transmitting portion. The light shielding layer includes an opening hole corresponding to the light transmitting portion region. The light shielding layer is removed from the open hole. The light shielding layer is formed of a metal or an inorganic film having an absorption coefficient lower than that of the metal removed from the light transmitting portion with respect to the wavelength of a laser beam used in a laser ablation process for removing the metal layer present in the light transmitting portion.

Referring to fig. 2, the display area DA includes pixels PIX1 and PIX2 arranged in a matrix form. Each of the pixels PIX1 and PIX2 may be implemented as a true type pixel in which R, G, and B sub-pixels of three primary colors are formed as one pixel. Each of the pixels PIX1 and PIX2 may further include a W sub-pixel omitted in the drawing. Further, two subpixels may be configured as one pixel using a subpixel rendering algorithm. For example, the first pixel PIX1 may be configured as an R sub-pixel and a G sub-pixel, and the second pixel PIX2 may be configured as a B sub-pixel and a G sub-pixel. The color under-representation in each of the pixels PIX1 and PIX2 may be compensated by an average value of the respective color data between adjacent pixels.

Referring to fig. 3, the first sensing area CA includes pixel groups PG spaced apart from each other by a predetermined distance D1 and a light-transmitting portion AG disposed between adjacent pixel groups PG. The lens 30 of the imaging element module receives external light through the light transmitting portion AG. The light-transmitting portion AG may include a transparent medium having a high transmittance without metal so that incident light may be lost with minimum light. In other words, the light-transmitting portion AG may be formed of a transparent insulating material that does not include metal lines or pixels. As the light transmission portion AG becomes larger, the transmittance of the first sensing region CA becomes higher.

The pixel group PG may include one or two pixels. Each pixel of the pixel group PG may include two to four sub-pixels. For example, one pixel in the pixel group PG may include an R sub-pixel, a G sub-pixel, and a B sub-pixel, or may include two sub-pixels, and may further include a W sub-pixel. In the example of fig. 3, the first pixel PIX1 is configured as an R sub-pixel and a G sub-pixel, and the second pixel PIX2 is configured as a B sub-pixel and a G sub-pixel, but the present disclosure is not limited thereto.

The distance D3 between the light-transmitting portions AG is smaller than the distance D1 between the pixel groups PG. The distance D2 between the sub-pixels is smaller than the distance D1 between the pixel groups PG.

The shape of the light-transmitting portion AG is illustrated as a circle in fig. 3, but the present disclosure is not limited thereto. For example, the light-transmitting portion AG may be designed in various shapes such as a circle, an ellipse, and a polygon. The transparent portion AG may be defined as an area of the screen where all metal layers are removed.

Fig. 4 is a diagram showing an overall configuration of a display device according to an embodiment of the present disclosure, and fig. 5 is a diagram schematically showing a configuration of a driving Integrated Circuit (IC) shown in fig. 4.

Referring to fig. 4 and 5, the display device includes a display panel 100 in which a pixel array is disposed on a screen, a display panel driving unit, and the like.

The pixel array of the display panel 100 includes data lines DL, gate lines GL crossing the data lines DL, and pixels P defined by the data lines DL and the gate lines GL and arranged in a matrix form. The pixel array further includes power supply lines such as the VDD line PL1, Vini line PL2, and VSS line PL3 as shown in fig. 6 and 7.

As shown in fig. 1, the pixel array may be divided into a circuit layer 12 and a light emitting element layer 14. The touch sensor array may be disposed on the light emitting element layer 14. Each pixel of the pixel array may include two to four sub-pixels as described above. Each sub-pixel comprises a pixel circuit arranged in the circuit layer 12.

The screen reproducing the input image on the display panel 100 includes a display area DA and a first sensing area CA.

The sub-pixels of each of the display area DA and the first sensing area CA include pixel circuits. The pixel circuit may include a driving element supplying current to the light emitting element OLED, a plurality of switching elements sampling a threshold voltage of the driving element and switching a current path of the pixel circuit, a capacitor holding a gate voltage of the driving element, and the like. The pixel circuit is disposed under the light emitting element OLED.

The first sensing area CA includes light-transmitting portions AG arranged between the pixel groups PG and an imaging element module 400 disposed below the first sensing area CA. The imaging element module 400 photoelectrically converts light incident through the first sensing area CA in an imaging mode using an image sensor, converts pixel data of an image output from the image sensor into digital data, and outputs photographed image data.

The display panel driving unit writes pixel data of an input image to the pixels P. The pixel P may be interpreted as a pixel group PG including a plurality of sub-pixels.

The display panel driving unit includes a data driving unit 306 supplying a data voltage of pixel data to the data lines DL and a gate driving unit 120 sequentially supplying a gate pulse to the gate lines GL. The data driving unit 306 may be integrated in the driving IC 300. The display panel driving unit may further include a touch sensor driving unit omitted in the drawing.

The driving IC 300 may be adhered to the display panel 100. The driving IC 300 receives pixel data and timing signals of an input image from the host system 200, supplies data voltages of the pixel data to the pixels, and synchronizes the data driving unit 306 and the gate driving unit 120.

The driving IC 300 is connected to the data lines DL through a data output channel to supply data voltages of pixel data to the data lines DL. The driving IC 300 may output a gate timing signal for controlling the gate driving unit 120 through the gate timing signal output channel. The gate timing signals generated from the timing controller 303 may include a gate start pulse VST, a gate shift clock CLK, and the like. The gate start pulse VST and the gate shift clock CLK swing between the gate-on voltage VGL and the gate-off voltage VGH. The gate timing signals VST and CLK output from the level shifter 307 are applied to the gate driving unit 120 to control the shifting operation of the gate driving unit 120.

The gate driving unit 120 may include a shift register formed on a circuit layer of the display panel 100 together with the pixel array. The shift register of the gate driving unit 120 sequentially supplies gate signals to the gate lines GL under the control of the timing controller 303. The gate signal may include a scan pulse and an EM pulse of the light emission signal. The shift register may include a scan driving unit outputting a scan pulse and an EM driving unit outputting an EM pulse. In fig. 5, GVST and GCLK are gate timing signals input to the scan driving unit. EVST and ECLK are gate timing signals input to the EM driving unit.

The driving IC 300 may be connected to the host system 200, the first memory 301, and the display panel 100. The driving IC 300 may include a data receiving and calculating unit 308, a timing controller 303, a data driving unit 306, a gamma compensation voltage generating unit 305, a power supply unit 304, a second memory 302, and the like.

The data receiving and calculating unit 308 includes a receiving unit that receives pixel data input as a digital signal from the host system 200 and a data calculating unit that processes the pixel data input through the receiving unit to improve image quality. The data calculation unit may include a data decoding unit that decodes and restores the compressed pixel data, an optical compensation unit that adds a preset optical compensation value to the pixel data, and the like. The optical compensation value may be set to a value that corrects the luminance of each pixel data based on the luminance of the screen measured from a camera image taken in the manufacturing process.

The timing controller 303 supplies pixel data of an input image received from the host system 200 to the data driving unit 306. The timing controller 303 generates a gate timing signal for controlling the gate driving unit 120 and a source timing signal for controlling the data driving unit 306 to control operation timings of the gate driving unit 120 and the data driving unit 306.

The timing controller 303 according to an embodiment generates a reference voltage control signal CREF for controlling a reference voltage according to PPI and supplies the reference voltage control signal CREF to the power supply unit 304. Since the display region where the pixels are arranged at the high PPI and the first sensing region where the pixels are arranged at the low PPI are previously defined, the timing controller 303 may control the reference voltage to be supplied to the pixels arranged at the high PPI and the pixels arranged at the low PPI according to the scan direction when performing the scan.

For example, the second reference voltage varies between the first voltage level and the second voltage level. The timing controller 303 generates a first reference voltage control signal when the second reference voltage is changed from the first voltage level to the second voltage level, and generates a second reference control signal when the second reference voltage is changed from the second voltage level to the first voltage level.

The power supply unit 304 generates power required for driving the pixel array, the gate driving unit 120, and the driving IC 300 of the display panel 100 using a Direct Current (DC) -DC converter. The DC-DC converter may include a charge pump, a regulator, a buck converter, a boost converter, and the like. The power supply unit 304 may regulate a DC input voltage received from the host system 200 to generate DC power such as a reference voltage, a gate-on voltage VGL, a gate-off voltage VGH, a pixel driving voltage VDD, a low potential power supply voltage VSS, and an initialization voltage Vini. The reference voltage is supplied to the gamma compensation voltage generating unit 305. The reference voltages include a first reference voltage and a second reference voltage. The first reference voltage is supplied to the first gamma compensation voltage generating unit 305a, and the second reference voltage is supplied to the second gamma compensation voltage generating unit 305 b. The gate-on voltage VGL and the gate-off voltage VGH are supplied to the level shifter 307 and the gate driving unit 120. Pixel power such as a pixel driving voltage VDD, a low potential power supply voltage VSS, and an initialization voltage Vini are commonly supplied to the pixels P. The initialization voltage Vini is set to a DC voltage lower than the pixel driving voltage VDD and lower than the threshold voltage of the light emitting element OLED to initialize the main node of the pixel circuit and suppress light emission of the light emitting element OLED.

The gamma compensation voltage generating unit 305 divides the reference voltage supplied from the power supply unit 304 by a voltage divider circuit to generate a gamma compensation voltage for gray scales. The gamma compensation voltage is an analog voltage set for each gray level of the pixel data. The gamma compensation voltage output from the gamma compensation voltage generation unit 305 is provided to the data driving unit 306.

The gamma compensation voltage generating unit 305 according to the embodiment includes a first gamma compensation voltage generating unit 305a and a second gamma compensation voltage generating unit 305 b. The first gamma compensation voltage generating unit 305a receives a first reference voltage to generate a first gamma compensation voltage for each gray scale, and the second gamma compensation voltage generating unit 305b receives a second reference voltage to generate a second gamma compensation voltage for each gray scale.

In this case, since the second data line group includes data lines connected to pixels arranged at a high PPI and pixels arranged at a low PPI in the second region of the screen, the second gamma compensation voltage generating unit 305b divides the second reference voltage to generate the second gamma compensation voltage different according to each PPI. For example, the second gamma compensation voltage generating unit 305b divides the first voltage level of the second reference voltage by the high PPI to generate the 2-1 gamma compensation voltage and divides the second voltage level of the second reference voltage by the low PPI to generate the 2-2 gamma compensation voltage in the second region.

The first and second gamma compensation

voltage generating units

305a and 305b may be independently controlled.

The data driving unit 306 converts digital data including pixel data received from the timing controller 303 into a gamma compensation voltage through a digital-to-analog converter (DAC), and outputs the data voltage. The data voltage output from the data driving unit 306 is supplied to the data lines DL of the pixel array through an output buffer connected to the data channel of the driving IC 300.

The data driving unit 306 according to the embodiment includes a first data driving unit 306a and a second data driving unit 306 b. Each channel of the first and second

data driving units

306a and 306b includes a DAC and an output buffer. The first data driving unit 306a converts digital data including pixel data received from the timing controller 303 into first gamma compensation voltages generated from the first gamma compensation voltage generating unit 305a through a DAC and supplies the data voltages to the first data line group of the pixel array through an output buffer. While scanning the pixels arranged in the second region with a high PPI, the second data driving unit 306b supplies a data voltage, which is obtained by converting digital data including pixel data received from the timing controller 303 into 2-1 gamma compensation voltages generated from the second gamma compensation voltage generating unit 305b through the DAC, to the second data line group of the pixel array through the output buffer. While scanning the pixels arranged at a low PPI in the second region, the second data driving unit 306b supplies a data voltage, which is obtained by converting digital data including pixel data received from the timing controller 303 into 2 nd-2 nd gamma compensation voltages generated from the second gamma compensation voltage generating unit 305b through the DAC, to the second data line group of the pixel array through the output buffer.

When power is input to the driving IC 300, the second memory 302 stores the compensation value, the register setting data, and the like received from the first memory 301. The compensation value may be applied to various algorithms for improving image quality. The compensation value may comprise an optical compensation value. The register setting data defines operations of the data driving unit 306, the timing controller 303, the gamma compensation voltage generating unit 305, and the like. The first memory 301 may include a flash memory. The second memory 302 may include a Static Random Access Memory (SRAM).

Host system 200 may be implemented as an Application Processor (AP). The host system 200 may transmit pixel data of an input image to the driving IC 300 through a Mobile Industry Processor Interface (MIPI). The host system 200 may be connected to the driving IC 300 through a Flexible Printed Circuit (FPC).

Meanwhile, the display panel 600 may be implemented as a flexible panel that may be applied to a flexible display. In the flexible display, the size of the screen can be changed by winding, folding, and bending the flexible panel, and the flexible display can be easily manufactured in various designs. The flexible display may be implemented as a rollable display, a foldable display, a bendable display, a slidable display, or the like. The flexible panel may be manufactured as a so-called "plastic OLED panel". The plastic OLED panel may include a back plate and an array of pixels on an organic thin film bonded to the back plate. A touch sensor array may be formed on the pixel array.

The back sheet may be a polyethylene terephthalate (PET) substrate. The pixel array and the touch sensor array may be formed on an organic thin film. The back plate may block moisture from penetrating into the organic thin film so that the pixel array is not exposed to moisture. The organic film may be a Polyimide (PI) substrate. The multi-layer buffer film may be formed of an insulating material not shown on the organic thin film. The circuit layer 12 and the light-emitting element layer 14 may be laminated on the organic thin film.

In the display device of the present disclosure, the pixel circuit, the gate driving unit, and the like disposed on the circuit layer 12 may include a plurality of transistors. The transistor may be implemented as an oxide TFT including an oxide semiconductor, a Low Temperature Polysilicon (LTPS) TFT including an LTPS, or the like. The transistor may be implemented as a p-channel TFT or an n-channel TFT. In the embodiment, an example in which the transistor of the pixel circuit is implemented as a p-channel TFT is mainly described, but the present disclosure is not limited thereto.

The transistor is a three-electrode element including a gate, a source, and a drain. The source is an electrode that supplies carriers to the transistor. In a transistor, carriers flow from the source. The drain is an electrode for moving carriers to the outside of the transistor. In a transistor, carriers flow from the source to the drain. In an n-channel transistor, since carriers are electrons, the source voltage is lower than the drain voltage, so that electrons can flow from the source to the drain. In an n-channel transistor, current flows from the drain to the source. In the p-channel transistor PMOS, since carriers are holes, the source voltage is higher than the drain voltage, so that holes flow from the source to the drain. In a p-channel transistor, since holes flow from a source to a drain, a current flows from the source to the drain. Note that the source and drain of the transistor are not fixed. For example, the source and drain may be varied according to the applied voltage. Accordingly, the present disclosure is not limited with respect to the source and drain of the transistor. In the following description, the source and the drain of the transistor will be referred to as a first electrode and a second electrode.

The gate pulse swings between a gate-on voltage and a gate-off voltage. The gate-on voltage is set to a voltage higher than the threshold voltage of the transistor, and the gate-off voltage is set to a voltage lower than the threshold voltage of the transistor. The transistor is turned on in response to a gate-on voltage and turned off in response to a gate-off voltage. In the n-channel transistor, the gate-on voltage may be a gate high voltage VGH, and the gate-off voltage may be a gate low voltage VGL. In the p-channel transistor, the gate-on voltage may be a gate low voltage VGL, and the gate-off voltage may be a gate high voltage VGH.

The drive elements of the pixel circuits may be implemented as transistors. In the driving element, the electrical characteristics among all pixels should be uniform, but may be different due to process variations and element characteristic variations and may vary with the lapse of display driving time. In order to compensate for the electrical characteristic deviation, the display device may include an internal compensation circuit and an external compensation circuit. The internal compensation circuit samples the threshold voltage Vth and/or the mobility μ of the driving element, which are added to the pixel circuit in each sub-pixel and vary according to the electrical characteristics of the driving element, and compensates for the variation in real time. The external compensation circuit transmits the threshold voltage and/or mobility of the driving element detected through the sensing line connected to each sub-pixel to the external compensation unit. The compensation unit of the external compensation circuit modulates the pixel data of the input image by reflecting the sensing result to compensate for the variation of the electrical characteristic of the driving element. Voltages of the pixels varying according to the electrical characteristics of the external compensation driving elements are detected, and the external circuit modulates data of the input image based on the detected voltages, thereby compensating for the electrical characteristic deviation of the driving elements between the pixels.

Fig. 6 and 7 are circuit diagrams showing examples of a pixel circuit to which an internal compensation circuit is applied. Fig. 8 is a diagram illustrating a driving method of the pixel circuit illustrated in fig. 6 and 7. It should be noted that the pixel circuit of the present disclosure is not limited to fig. 6 and 7. The pixel circuits shown in fig. 6 and 7 may be equally applied to the pixel circuits of the display area DA and the first sensing area CA. A pixel circuit applicable to the present disclosure may be implemented as the circuits shown in fig. 13 and 14, however, the present disclosure is not limited thereto.

Referring to fig. 6 to 8, the pixel circuit includes a light emitting element OLED, a driving element DT supplying current to the light emitting element OLED, and an internal compensation circuit sampling a threshold voltage Vth of the driving element DT using a plurality of switching elements M1 to M6 and compensating a gate voltage of the driving element DT by the threshold voltage Vth of the driving element DT. Each of the driving element DT and the switching elements M1 to M6 may be implemented as a p-channel TFT.

As shown in fig. 8, the driving period of the pixel circuit using the internal compensation circuit may be divided into an initialization period Tini, a sampling period Tsam, and a light emission period Tem.

During the initialization period Tini, the (N-1) th SCAN pulse SCAN (N-1) is generated as a pulse of the gate-on voltage VGL, and the voltage of each of the nth SCAN pulse SCAN (N) and the light emission pulse em (N) is the gate-off voltage VGH. During the sampling period Tsam, the nth SCAN pulse SCAN (N) is generated as a pulse of the gate-on voltage VGL, and the voltage of each of the (N-1) th SCAN pulse SCAN (N-1) and the emission pulse em (N) is the gate-off voltage VGH. During at least a portion of the emission period Tem, the emission pulse em (N) is generated as the gate-on voltage VGL, and a voltage of each of the (N-1) th SCAN pulse SCAN (N-1) and the nth SCAN pulse SCAN (N) is generated as the gate-off voltage VGH.

During the initialization, the fifth switching element M5 is turned on according to the gate-on voltage VGL of the (N-1) th SCAN pulse SCAN (N-1) to initialize the pixel circuit. During the sampling period Tsam, the first and second switching elements M1 and M2 are turned on according to the gate-on voltage VGL of the nth scan pulse scan (N), thereby sampling and storing the threshold voltage of the driving element DT in the storage capacitor Cst 1. Meanwhile, the sixth switching element M6 is turned on during the sampling period Tsam to lower the voltage of the fourth node n4 to the reference voltage Vref to suppress light emission of the light emitting element OLED. During the light emission period Tem, the third switching element M3 and the fourth switching element M4 are turned on, so that the light emitting element OLED emits light. In the emission period Tem, in order to accurately represent the luminance of the low gray scale with the duty ratio of the emission pulse em (n), the emission pulse em (n) swings between the gate-on voltage VGL and the gate-off voltage VGH at a predetermined duty ratio, and thus the third switching element M3 and the fourth switching element M4 may be repeatedly turned on and off.

The light emitting element OLED may be implemented as an OLED or an inorganic light emitting diode. Hereinafter, an example in which the light emitting element OLED is implemented as an OLED will be described.

The light emitting element OLED may include an organic compound layer formed between an anode and a cathode. The organic compound layer may include a hole injection layer HIL, a hole transport layer HTL, an emission layer EML, an electron transport layer ETL, and an electron injection layer EIL, but the disclosure is not limited thereto. When a voltage is applied to the anode and the cathode of the OLED, holes passing through the hole transport layer HTL and electrons passing through the electron transport layer ETL are moved to the light emitting layer EML to form excitons, thereby emitting visible light from the light emitting layer EML.

The anode of the light emitting element OLED is connected to the fourth node n4 between the fourth switching element M4 and the sixth switching element M6. The fourth node n4 is connected to the anode of the light emitting element OLED, the second electrode of the fourth switching element M4, and the second electrode of the sixth switching element M6. The cathode of the light emitting element OLED is connected to a VSS line PL3 to which a low potential power supply voltage VSS is applied. The light emitting element OLED emits light with a current Ids flowing due to the gate-source voltage Vgs of the driving element DT. The current path of the light emitting element OLED is switched by the third switching element M3 and the fourth switching element M4.

The storage capacitor Cst1 is connected between the VDD line PL1 and the first node n 1. The data voltage Vdata compensated by the threshold voltage Vth of the driving element DT is charged in the storage capacitor Cst 1. Since the data voltage in each sub-pixel is compensated by the threshold voltage Vth of the driving element DT, the characteristic deviation of the driving element DT is compensated in the sub-pixel.

The first switching element M1 is turned on in response to the gate-on voltage VGL of the nth scan pulse scan (N) to connect the second node N2 and the third node N3. The second node n2 is connected to the gate electrode of the driving element DT, the first electrode of the storage capacitor Cst1, and the first electrode of the first switching element M1. The third node n3 is connected to the second electrode of the driving element DT, the second electrode of the first switching element M1, and the first electrode of the fourth switching element M4. The gate of the first switching element M1 is connected to the first gate line GL1 to receive the nth scan pulse scan (N). A first electrode of the first switching element M1 is connected to the second node n2, and a second electrode of the first switching element M1 is connected to the third node n 3.

Since the first switching element M1 is turned on only during the very short horizontal period 1H in which the nth scan pulse scan (N) is generated as the gate-on voltage VGL in one frame period, an off-state of about one frame period is maintained, a leakage current may be generated in the off-state of the first switching element M1. In order to suppress the leakage current of the first switching element M1, as shown in fig. 7, the first switching element M1 may be implemented as a transistor having a double gate structure in which two transistors M1a and M1b are connected in series.

The second switching element M2 is turned on in response to the gate-on voltage VGL of the nth scan pulse scan (N) to supply the data voltage Vdata to the first node N1. The gate of the second switching element M2 is connected to the first gate line GL1 to receive the nth scan pulse scan (N). A first electrode of the second switching element M2 is connected to the first node n 1. The second electrode of the second switching element M2 is connected to the data line DL to which the data voltage Vdata is applied. The first node n1 is connected to a first electrode of the second switching element M2, a second electrode of the third switching element M3, and a first electrode of the driving element DT.

The third switching element M3 is turned on in response to the gate-on voltage VGL of the light emission pulse em (n) to connect the VDD line PL1 to the first node n 1. The gate of the third switching element M3 is connected to the third gate line GL3 to receive the light emitting pulse em (n). A first electrode of the third switching element M3 is connected to the VDD line PL 1. A second electrode of the third switching element M3 is connected to the first node n 1.

The fourth switching element M4 is turned on in response to the gate-on voltage VGL of the light emission pulse em (n) to connect the third node n3 to the anode of the light emitting element OLED. The gate of the fourth switching element M4 is connected to the third gate line GL3 to receive the light emitting pulse em (n). A first electrode of the fourth switching element M4 is connected to the third node, and a second electrode of the fourth switching element M4 is connected to the fourth node n 4.

The fifth switching element M5 is turned on in response to the gate-on voltage VGL of the N-1 th SCAN pulse SCAN (N-1) to connect the second node to the Vini line PL 2. The gate of the fifth switching element M5 is connected to the second gate line GL2 to receive the (N-1) th SCAN pulse SCAN (N-1). A first electrode of the fifth switching element M5 is connected to the second node n2, and a second electrode of the fifth switching element M5 is connected to the Vini line PL 2. In order to suppress the leakage current of the fifth switching element M5, as shown in fig. 7, the fifth switching element M5 may be implemented as a transistor having a double gate structure in which two transistors M5a and M5b are connected in series.

The sixth switching element M6 is turned on in response to the gate-on voltage VGL of the nth scan pulse scan (N) to connect the Vini line PL2 to the fourth node N4. The gate of the sixth switching element M6 is connected to the first gate line GL1 to receive the nth scan pulse scan (N). A first electrode of the sixth switching element M6 is connected to the Vini line PL2, and a second electrode of the sixth switching element M6 is connected to the fourth node n 4.

The driving element DT drives the light emitting element OLED by adjusting the current Ids flowing in the light emitting element OLED according to the gate-source voltage Vgs. The driving element DT includes a gate connected to the second node n2, a first electrode connected to the first node, and a second electrode connected to the third node n 3.

During the initialization period Tini, as shown in fig. 8, the (N-1) th SCAN pulse SCAN (N-1) is generated as the gate-on voltage VGL. During the initialization period Tini, the nth scan pulse scan (N) and the emission pulse em (N) maintain the gate-off voltage VGH. Accordingly, during the initialization period Tini, the fifth switching element M5 is turned on, and thus the second node n2 and the fourth node n4 are initialized to the initialization voltage Vini. The hold period Th may be set between the initialization period Tini and the sampling period Tsam. In the holding period Th, the gate pulses SCAN (N-1), SCAN (N), and em (N) hold their previous states.

During the sampling period Tsam, the nth scan pulse scan (N) is generated as the gate-on voltage VGL. The pulse of the nth scan pulse scan (N) is synchronized with the data voltage Vdata of the nth pixel line. The (N-1) th SCAN pulse SCAN (N-1) and the emission pulse EM (N) hold the gate-off voltage VGH during the sampling period Tsam. Accordingly, during the sampling period Tsam, the first and second switching elements M1 and M2 are turned on.

During the sampling period Tsam, the gate voltage DTG of the driving element DT is increased by the current flowing through the first and second switching elements M1 and M2. When the driving element DT is turned off, the gate node voltage DTG is Vdata | Vth |. In this case, the voltage of the first node n1 is Vdata | Vth |. During the sampling period Tsam, the gate-source voltage Vgs of the driving element DT is | Vgs | ═ Vdata- (Vdata- | Vth |) | Vth |.

During the emission period Tem, an emission pulse em (n) may be generated as the gate-on voltage VGL. During the emission period Tem, in order to improve low gray scale representation, the emission pulse em (n) is turned on and off at a predetermined duty ratio, and thus may swing between the gate-on voltage VGL and the gate-off voltage. Accordingly, during at least a part of the emission period Tem, the emission pulse em (n) may be generated as the gate-on voltage VGL.

When the light emission pulse em (n) is the gate-on voltage VGL, a current flows between VDD and the light emitting element OLED, and thus the light emitting element OLED may emit light. The (N-1) th SCAN pulse SCAN (N-1) And an nth scan pulse scan (N) to maintain the gate-off voltage VGH. During the light emission period Tem, the third switching element M3 and the fourth switching element M4 are repeatedly turned on and off according to the voltage of the light emission signal EM. When the light emission pulse em (n) is the gate-on voltage VGL, the third switching element M3 and the fourth switching element M4 are turned on, and thus a current flows in the light emitting element OLED. In this case, Vgs of the driving element DT is | Vgs | ═ VDD- (Vdata- | Vth |), and the current flowing in the light emitting element OLED is K (VDD-Vdata)². K denotes a constant value determined by the charge mobility, parasitic capacitance, channel capacity, and the like of the driving element DT.

Fig. 9 to 12H are diagrams illustrating examples in which the gamma reference voltage varies according to each region of the display panel.

Referring to fig. 9, the screen of the display panel 100 according to the embodiment includes a display region DA in which pixels are arranged at a high resolution and a first sensing region CA in which pixels are arranged at a low resolution, and is divided into a first region 110a including pixels arranged at a high PPI and a second region 110b including pixels arranged at a high PPI and pixels arranged at a low PPI. The data lines connected to the pixel array of the display panel 100 are classified into a first data line group DL1 including data lines connected to pixels arranged in the first region and a second data line group DL2 including data lines connected to pixels arranged in the second region. Here, the first and second regions 110a and 110B are divided into portions B1, a, and B2 in the scanning direction.

Here, the first data line group DL1 includes data lines connected to pixels arranged at a high PPI in the first region, and the second data line group DL2 includes data lines connected to pixels arranged at a high PPI and pixels arranged at a low PPI in the second region.

Here, an example case where the first sensing area CA is formed in the middle of the display area DA has been described, however, the present disclosure is not limited thereto, and the first sensing area CA may be formed at various positions.

Since the PPI of the first sensing region CA is greater than that of the display region DA, when the pixels of the display region DA and the pixels of the first sensing region CA are driven at the same gray scale within the same dynamic range of the data voltage, the luminance of the first sensing region CA may be lower than that of the display region DA. Therefore, in the embodiment, it is attempted to increase the luminance of the pixels in the first sensing area CA by expanding the dynamic range of the data voltage applied to the pixels of the first sensing area CA.

Fig. 10 is a graph illustrating data voltages applied to pixels of the display region and data voltages applied to pixels of the first sensing region. Here, the "PGMA range" represents an output voltage range of the gamma compensation voltage generating unit 305.

Referring to fig. 10, since the PPI of the first sensing region CA is lower than that of the display region DA, when the pixels in the first sensing region CA are driven, the power supply unit 304 changes the reference voltage and supplies the changed reference voltage to the gamma compensation voltage generating unit 305, the gamma compensation voltage generating unit 305 generates the gamma compensation voltage for the gray scale by using the changed reference voltage, and the data driving unit 306 expands the dynamic range of the data voltage applied to the pixels in the first sensing region CA by using the generated gamma compensation voltage for the gray scale. Accordingly, the dynamic range DR' of the data voltage applied to the pixels arranged with the low PPI is greater than the dynamic range DR of the data voltage applied to the pixels arranged with the high PPI.

Referring to fig. 9, 11A and 11B, since the first data line group DL1 includes data lines connected to pixels arranged at a high PPI in the first region, the pixel power supply unit 304 supplies the first reference voltage to the first gamma compensation voltage generating unit 305a while scanning the data lines connected to the first data line group DL 1.

Referring to fig. 9, 12A and 12B, since the second data line group DL2 includes a data line connected to pixels arranged at a high PPI in the second region and a data line connected to pixels arranged at a low PPI, the power supply unit 304 supplies different reference voltages to the second gamma compensation voltage generating unit 305B according to each PPI. That is, while scanning the pixels connected to the data lines of the second data line group DL2 and arranged with high PPI, the power supply unit 304 supplies the second reference voltage to the second gamma compensation voltage generating unit 305b, and changes the second reference voltage of the second voltage level to supply the changed second reference voltage to the second gamma compensation voltage generating unit 305 b. Here, the change of the second reference voltage refers to a change of a voltage level of the second reference voltage.

In the embodiment, the exemplary case where the pixel circuit is implemented as the p-type transistor is described, and thus the gamma compensation voltage of the high gray data voltage may be implemented as the negative gamma compensation voltage.

For example, when a transistor driving a light emitting element of a pixel is implemented as a p-channel Metal Oxide Semiconductor Field Effect Transistor (MOSFET), and when a data voltage is applied to a gate of the transistor, a negative gamma compensation voltage is generated. Therefore, as the gray scale of the pixel data RGB becomes larger, the gamma compensation voltage becomes smaller.

In this case, the first reference voltage and the second reference voltage may have different dynamic ranges. For example, the dynamic range of the second reference voltage is set to be larger than the dynamic range of the first reference voltage.

In an embodiment, the analog reference voltage may be changed such that a slope constant with time is provided at the boundary portion of the first sensing area CA, thereby additionally compensating for the boundary portion of the photographing area.

Referring to fig. 12C to 12H, in an embodiment, an analog reference voltage varying with time may be supplied in a boundary portion between the display area DA and the first sensing area CA. Here, the analog reference voltage is supplied to the boundary portion in a form having a constant slope with time. A voltage between a first voltage level and a second voltage level of the second reference voltage is supplied to the boundary portion.

For example, the region in which the reference voltage is changed may be the display region DA, the first sensing region CA, and a region including the display region DA and the first sensing region CA.

The fact that the analog reference voltage has a constant slope with time in the boundary portion means that the dynamic range of the data voltage applied to the pixels adjacent to the boundary portion (i.e., the pixels in the display area or the pixels in the first sensing area) is gradually expanded. Accordingly, the brightness gradually increases at the boundary portion between the display area DA and the first sensing area CA.

Referring to fig. 12D, the analog reference voltage gradually changes in the boundary region between the portions B1 and B2 where the pixels are arranged at a high PPI and the portion a where the pixels are arranged at a low PPI in the second region. The changed boundary region includes pixels PX _ B11, PX _ B12, PX _ B21, and PX _ B22, which are adjacent to the section a where the pixels are arranged at the low PPI, among the pixels in the sections B1 and B2 where the pixels are arranged at the high PPI.

The analog reference voltage varies in a region where the pixels are arranged with a high PPI.

Referring to fig. 12E, in the boundary region between the portions B1 and B2 in which the pixels are arranged at a high PPI and the portion a in which the pixels are arranged at a low PPI in the second region, the analog reference voltage gradually changes. The changed boundary region includes pixels PX _ a11, PX _ a12, PX _ a21, and PX _ a22, which are adjacent to the section a where the pixels are arranged at the low PPI, among the pixels in the sections B1 and B2 where the pixels are arranged at the high PPI.

The analog reference voltage varies in a region where the pixels are arranged with a low PPI.

Referring to fig. 12F, in the boundary region between the portions B1 and B2 in which the pixels are arranged at a high PPI and the portion a in which the pixels are arranged at a low PPI in the second region, the analog reference voltage gradually changes. The changed boundary region includes pixels PX _ B12, PX _ a11, PX _ B21, and PX _ a22 adjacent to each other between the sections B1 and B2 where the pixels are arranged at a high PPI and the section a where the pixels are arranged at a low PPI.

The analog reference voltage varies over a region where the pixels are arranged with a high PPI and a region where the pixels are arranged with a low PPI.

In this case, the portion where the analog reference voltage varies may be a boundary region, but the present disclosure is not limited thereto. Since the purpose of the boundary portion compensation is to reduce the recognition of the boundary portion in the image, the optimum variable shape can be obtained through experimental cognitive evaluation. For example, it may be designed that the portion of the analog reference voltage change starts or ends at the boundary portion, and the analog reference voltage is increased rapidly or gradually instead of the constant slope.

In this way, in the second data line group, the reference voltage may be varied according to each PPI. For this, in the embodiment, the gamma compensation voltage generating units connected to the respective data line groups (i.e., the first data line group and the second data line group) are respectively configured.

Referring to fig. 12G and 12H, examples of variations of reference voltages applied to the second data line group when the pixel circuit according to the embodiment is implemented as an n-type transistor are illustrated. The gamma compensation voltage of the high gray data voltage may be implemented as a positive gamma compensation voltage.

For example, when a transistor driving a light emitting element (i.e., OLED) of a pixel is implemented as an n-channel MOSFET, and when a data voltage is applied to a gate of the transistor, a positive gamma compensation voltage is generated. Therefore, as the gray scale of the pixel data RGB becomes larger, the gamma compensation voltage becomes smaller.

In this case, the portion where the analog reference voltage varies may be a boundary portion, however, the present disclosure is not limited thereto.

Such a driving IC providing gamma compensation voltages for the entire gray scale is applied to mobile devices and Televisions (TVs). The configuration of the driving IC is applied to mobile devices and TVs in various forms. In the mobile device, a gamma reference voltage is generated inside a driving IC by external control, and a compensation voltage for the entire gray scale is generated based on the generated gamma reference voltage. In the TV, a gamma reference voltage generated by an external device is used to generate a compensation voltage for the entire gray scale in the driving IC. In this case, in the mobile device, the high gray data voltage is changed by an external device using a code, and in the TV, the high gray data voltage is changed and supplied by the external device.

Fig. 13A and 13B are diagrams illustrating a configuration of a driving IC applied to a mobile device.

Referring to fig. 13A, a gamma compensation voltage generating unit 305 is formed in a driving IC 300 applied to a mobile device. The gamma compensation voltage generating unit 305 includes a first circuit unit 51 receiving the reference voltage REFL and generating a plurality of gamma reference voltages GMA1, GMA8, and GMA9, a second circuit unit 52 selecting and generating gamma reference voltages GMA2 to GAM7 other than the gamma reference voltages GMA1, GMA8, and GMA9 selected by the first circuit unit 51, and a third circuit unit 53 dividing the gamma reference voltages GMA1 to GMA9 from the first circuit unit 51 and the second circuit unit 52 and generating gamma compensation voltages for the entire gray scale.

The first circuit unit 51 divides the reference voltage VREFL input from the power supply unit 136 and determines a first gamma reference voltage GMA1, an eighth gamma reference voltage GMA8, and a ninth gamma reference voltage GMA9 based on the divided voltages. The voltage levels of gamma reference voltages GMA1, GMA8 and GMA9 may be adjusted according to register settings RGMA1, RGMA8 and RGMA 9. The first circuit unit 51 includes a first voltage divider circuit RS1, a voltage selection unit MUX11 to MUX13, and a plurality of buffers BUF11 to BUF 13.

The first voltage divider circuit RS1 receives the gamma reference voltage VREFL from the power supply unit 136. The first voltage divider circuit RS1 divides the gamma reference voltage VREFL using an R-string circuit including resistors connected in series.

The voltage selection unit includes a multiplexer MUX11 selecting a first gamma reference voltage GMA1 from the voltages divided by the first voltage divider circuit RS1 according to a register set value RGMA1, a multiplexer MUX13 selecting an eighth gamma reference voltage GMA8 from the voltages divided by the first voltage divider circuit RS1 according to a register set value RGMA8, and a multiplexer MUX12 selecting a ninth gamma reference voltage GMA9 from the voltages divided by the first voltage divider circuit RS1 according to a register set value RGMA 9.

The first gamma reference voltage GMA1 is the highest gamma compensation voltage. The ninth gamma reference voltage GMA9 is the lowest gamma compensation voltage. The eighth gamma reference voltage GMA8 is a gamma tag voltage higher than the ninth gamma reference voltage GMA 9.

The second circuit unit 52 receives the first and eighth gamma reference voltages GMA1 and GMA8 input from the first circuit unit 51, divides the first gamma reference voltage GMA1, and determines the second to eighth gamma reference voltages GMA2 to GMA 8. The voltage levels of the gamma reference voltages GMA2 to GMA7 may be adjusted according to register set values RGMA2 to RGMA 7.

The second circuit unit 52 includes a second voltage divider circuit RS2, a voltage selection unit MUX21 to MUX27, and a plurality of buffers BUF21 to BUF 27.

The second voltage divider circuit RS2 is divided into a 2-1 st voltage divider circuit RS21 to a 2-6 th voltage divider circuit RS 26. Each of the 2-1 st voltage divider circuit RS21 to the 2-6 th voltage divider circuit RS26 divides an input voltage using an R string circuit including resistors connected in series. The voltage selection units MUX21 to MUX26 include a 2-1 st multiplexer MUX21 connected between the 2-1 st voltage divider circuit RS21 and the 2-1 st buffer BUF21, a 2-2 nd multiplexer MUX22 connected between the 2-2 nd voltage divider circuit RS22 and the 2-2 nd buffer BUF22, a 2-3 rd multiplexer MUX23 connected between the 2-3 rd voltage divider circuit RS23 and the 2-3 rd buffer BUF23, a 2-4 th multiplexer MUX24 connected between the 2-4 th voltage divider circuit RS24 and the 2-4 th buffer BUF24, a 2-5 th multiplexer MUX25 connected between the 2-5 th voltage divider circuit RS25 and the 2-5 th buffer BUF25, and a 2-6 th multiplexer MUX26 connected between the 2-6 th voltage divider circuit RS26 and the 2-6 th buffer BUF 26.

The 2-1 th voltage divider circuit RS21 receives a first gamma reference voltage GMA1 and an eighth gamma reference voltage GMA8, divides the first gamma reference voltage GMA1, and outputs different voltages through nodes between resistors. The 2-1 st multiplexer MUX21 selects one of the voltages divided by the 2-1 st voltage divider circuit R21 as a second gamma reference voltage GMA2 according to a register set value RGMA 2. The 2-1 th buffer BUF21 supplies a second gamma reference voltage GMA2 input from the 2-1 th multiplexer MUX21 to a node between the 3-1 th voltage divider circuit RS31 and the 3-2 th voltage divider circuit RS 32.

The 2-2 th voltage divider circuit RS22 receives the second gamma reference voltage GMA2 and the eighth gamma reference voltage GMA8, divides the second gamma reference voltage GMA2, and outputs different voltages through nodes between resistors. The 2 nd-2 nd multiplexer MUX22 selects one of the voltages divided by the 2 nd-2 nd voltage divider circuit RS22 as the third gamma reference voltage GMA3 according to the register set value RGMA 3. The 2-2 buffer BUF22 supplies a third gamma reference voltage GMA3 input from the 2-2 multiplexer MUX22 to a node between the 3-2 divider circuit RS32 and the 3-3 divider circuit RS 33.

The 2-6 th voltage divider circuit RS26 receives a sixth gamma reference voltage GMA6 and an eighth gamma reference voltage GMA8, divides the sixth gamma reference voltage GMA6, and outputs different voltages through nodes between resistors. The 2-6 th multiplexer MUX26 selects one of the voltages divided by the 2-6 th voltage divider circuit RS26 as a seventh gamma reference voltage GMA7 according to a register set value RGMA 7. The 2-6 th buffer BUF26 supplies a seventh gamma reference voltage GMA7 input from the 2-6 th multiplexer MUX26 to a node between the 3-6 th voltage divider circuit RS36 and the 3-7 th voltage divider circuit RS 37.

The third circuit unit 53 receives gamma reference voltages GMA1 to GMA9, divides the gamma reference voltages GMA1 to GMA9, and outputs gamma compensation voltages of entire gray scales that can be expressed in pixel data of an input image. The third circuit unit 53 includes a third voltage divider circuit RS 3.

Each of the 3-1 st to 3-8 th voltage divider circuits RS31 to RS38 divides an input voltage using an R string circuit including resistors connected in series. The 3-1 th voltage divider circuit RS31 divides the first and second gamma reference voltages GMA1 and GMA2 and outputs a gamma compensation voltage for a gray scale between the first and second gamma reference voltages GMA1 and GMA 2. The 3-2 divider circuit RS32 divides the second and third gamma reference voltages GMA2 and GMA3 and outputs a gamma compensation voltage for a gray scale between the second and third gamma reference voltages GMA2 and GMA 3. The 3-6 th voltage divider circuit RS36 divides the sixth and seventh gamma reference voltages GMA6 and GMA7 and outputs a gamma compensation voltage for a gray scale between the sixth and seventh gamma reference voltages GMA6 and GMA 7. The 3-7 th voltage divider circuit RS37 divides the seventh and eighth gamma reference voltages GMA7 and GMA8 and outputs a compensation voltage for a gray scale between the seventh and eighth gamma reference voltages GMA7 and GMA 8. The 3-8 voltage divider circuit RS38 divides the eighth and ninth gamma reference voltages GMA8 and GMA9 and outputs a gamma compensation voltage for a gray scale between the eighth and ninth gamma reference voltages GMA8 and GMA 9.

In this case, the gamma reference voltage VREFH may be commonly used when the pixel circuits are implemented as p-type transistors, and the gamma reference voltage VREFL may be commonly used when the pixel circuits are implemented as n-type transistors.

Referring to fig. 13B, the driving IC 300 applied to the mobile device according to the embodiment includes therein two gamma compensation voltage generating units 305 connected to the first data line region and the second data line region.

The gamma compensation voltage generating unit according to the embodiment is configured by connecting the gamma compensation voltage generating unit shown in fig. 13A and 13B to the first data line group and the second data line group, and since the circuit configuration and the operation principle thereof are substantially the same, a detailed description thereof will be omitted.

Here, the first gamma compensation voltage generating unit 305a receives the first reference voltage VREFL1 from the power supply unit 304 to generate gamma reference voltages and generates first gamma compensation voltages for gray scales using the gamma reference voltages, and the second gamma compensation voltage generating unit 305b receives the second reference voltage VREFL2 from the power supply unit 304 to generate gamma reference voltages and generates second gamma compensation voltages for gray scales different according to each PPI using the gamma reference voltages.

The second gamma compensation voltage generating unit 305b divides a first voltage level of the second reference voltage to generate gamma reference voltages, and generates 2-1 gamma compensation voltages for gray scales using the gamma reference voltages.

The second gamma compensation voltage generating unit 305b divides a second voltage level of the second reference voltage to generate gamma reference voltages, and generates 2 nd-2 nd gamma compensation voltages for gray scales using the gamma reference voltages.

Fig. 14A and 14B are diagrams illustrating a configuration of a driving IC applied to a display device.

Referring to fig. 14A, a driving IC 300 applied to a TV has a portion of a gamma compensation voltage generating unit 305 formed therein. The gamma compensation voltage generating unit 305 includes a first circuit unit 51 receiving the reference voltage REFL and generating a plurality of gamma reference voltages GMA1, GMA8, and GMA9, a second circuit unit 52 selecting and generating gamma reference voltages GMA2 to GAM7 other than the gamma reference voltages GMA1, GMA8, and GMA9 selected by the first circuit unit 51, and a third circuit unit 53 dividing the gamma reference voltages GMA1 to GMA9 from the first circuit unit 51 and the second circuit unit 52 and generating gamma compensation voltages for the entire gray scale.

The first circuit unit 51 and the second circuit unit 52 are disposed outside the driving IC 300, and the third circuit unit 53 is disposed inside the driving IC 300. Accordingly, the first and

second circuit units

51 and 52 outside the drive IC 300 generate gamma reference voltages GMA1 to GMA9 to supply the generated gamma reference voltages GMA1 to GMA9 to the third circuit unit 53 inside the drive IC 300, and the third circuit unit 53 inside the drive IC 300 divides the supplied gamma reference voltages GMA1 to GMA9 to generate gamma compensation voltages for the entire gray scale.

Referring to fig. 14B, the driving IC 300 applied to a TV according to the embodiment includes two gamma compensation voltage generating units 305a and 305B connected to the first data line group and the second data line group and third circuit units 53a and 53B of the two gamma compensation voltage generating units 305a and 305B.

The gamma compensation

voltage generating units

305a and 305b according to the embodiment are configured by connecting the gamma compensation voltage generating units shown in fig. 15 to the first data line group and the second data line group, and since the circuit configuration and the operation principle thereof are substantially the same, the detailed description thereof will be omitted.

Here, the third circuit unit 53a of the first gamma compensation voltage generating unit 305a receives the gamma reference voltage from the outside of the driving IC 300 to generate the first gamma compensation voltage for the gray scale, and the third circuit unit 53b of the second gamma compensation voltage generating unit 305b receives the gamma reference voltage from the outside of the driving IC 300 to generate the second gamma compensation voltage for the gray scale, which is different according to each PPI.

Fig. 15 is a block diagram schematically showing a configuration of a data driving unit according to an embodiment.

Referring to fig. 15, the data driving unit 306 includes a first DAC1, a second DAC2, a first output buffer BUF1, and a second output buffer BUF 2. Here, the data driving unit 306 includes a first data driving unit 306a and a second data driving unit 306 b. The first data driving unit 306a is connected to the first gamma compensation voltage generating unit 305a, and the second data driving unit 306b is connected to the second gamma compensation voltage generating unit 305 b.

The first DAC1 converts digital data including pixel data received from the timing controller 303 into a first gamma compensation voltage to output a data voltage. The first output buffer BUF1 is connected to the output node of the first DAC1 to supply the data voltage output from the first DAC1 to the data lines DL of the pixel array.

The second DAC2 converts digital data including pixel data received from the timing controller 303 into a first gamma compensation voltage to output a data voltage, or converts the digital data into a second gamma compensation voltage to output a data voltage. The second output buffer BUF2 is connected to the output node of the second DAC2 to supply the data voltage output from the second DAC2 to the data lines DL of the pixel array.

Fig. 16 is a diagram illustrating a display device to which a fingerprint recognition module is applied according to an embodiment, and fig. 17 is a diagram illustrating an example of pixels and photosensors in the second sensing region SA.

Referring to fig. 16, the display device includes a display panel 100 in which a pixel array is arranged on a screen, a display panel driving unit, and the like. The screen reproducing the input image on the display panel 100 includes a display area DA and a second sensing area SA.

In the display area DA and the second sensing area SA, each sub-pixel of the display pixel includes a pixel circuit. The pixel circuit may include a driving element supplying current to the light emitting element OLED, a plurality of switching elements sampling a threshold voltage of the driving element and switching a current path of the pixel circuit, a capacitor holding a gate voltage of the driving element, and the like.

The second sensing region SA includes pixels to which pixel data is written, and sensor pixels S spaced apart from each other at predetermined intervals with the pixels interposed therebetween. The sensor pixel S includes a photosensor and a photosensor driving circuit that drives the photosensor. The display pixels in the second sensing area SA emit light according to the data voltage of the pixel data to display the input data in the display mode, but emit light of high brightness according to the voltage of the light source driving data, and thus are driven as the light source in the fingerprint recognition mode. The light source driving data is data independent of the pixel data of the input image.

Referring to fig. 17, the second sensing region SA includes pixel groups PG spaced apart from each other by a predetermined distance D1 and sensor pixels S arranged between adjacent pixel groups PG and spaced apart from each other at regular intervals.

The pixel group PG may include one or two pixels. Each pixel of the pixel group PG may include two to four sub-pixels. For example, one pixel in the pixel group PG may include an R sub-pixel, a G sub-pixel, and a B sub-pixel, or may include two sub-pixels, and may further include a W sub-pixel. The first pixel PIX1 may be configured as an R sub-pixel and a G sub-pixel, and the second pixel PIX2 may be configured as a B sub-pixel and a G sub-pixel. Each photosensor S includes an organic/inorganic photodiode. The distances D4 between adjacent photosensors S are substantially the same in the four directions X, Y, Θ x, and Θ y. The X-axis and Y-axis represent two orthogonal directions. Θ X and Θ Y represent tilt axis directions offset by 45 degrees from the X-axis and Y-axis, respectively.

Fig. 18A and 18B are diagrams illustrating an operation of the second sensing region illustrated in fig. 17.

Referring to fig. 18A, the pixels of the second sensing region SA may be in a power-off state, a standby mode, and a non-driving state in a non-driving frame period during low-speed driving. In the non-driven state, the pixel does not emit light. In the non-driving state, the photosensor S may not be driven in order to reduce power consumption.

Referring to fig. 18B, in the display mode, the pixels in the second sensing region SA may charge the data voltage of the pixel data and emit light with a luminance according to the gray value of the pixel data. Accordingly, in the display mode, the second sensing region SA may display an input image.

In this way, it can be seen that in the second sensing region SA of the display device to which the fingerprint recognition module is applied, the photo sensors S are disposed between the pixel group PG and the adjacent pixel group PG, and in a display mode in which an input image is displayed, since only the pixels emit light, the pixels are disposed with a low PPI to correspond to the structure of the first sensing region CA (in which the light-transmitting portion AG is disposed between the pixel group PG and the adjacent pixel group PG).

Accordingly, as proposed in the present disclosure, a screen may be divided into a first region including pixels arranged at high resolution and a second region including pixels arranged at high resolution and pixels arranged at low resolution, a first gamma compensation voltage generated by dividing a first reference voltage may be applied to the first region, and a different second gamma compensation voltage generated by dividing a first voltage level and a second voltage level of a second reference voltage according to respective resolutions may be applied to the second region.

Referring to fig. 19, the display device includes a display panel 100 in which a pixel array is arranged on a screen, a display panel driving unit, and the like. The screen reproducing the input image on the display panel 100 includes a display area DA, a first sensing area CA, and a second sensing area SA.

The sub-pixels of each of the display area, the first sensing area CA, and the second sensing area SA include pixel circuits. The pixel circuit may include a driving element supplying current to the light emitting element OLED, a plurality of switching elements sampling a threshold voltage of the driving element and switching a current path of the pixel circuit, a capacitor holding a gate voltage of the driving element, and the like.

The first sensing area CA includes light-transmitting portions AG arranged between the pixel groups PG and an imaging element module disposed below the first sensing area CA. The imaging element module photoelectrically converts light incident through the first sensing area CA in an imaging mode using an image sensor, converts pixel data of an image output from the image sensor into digital data, and outputs photographed image data.

The second sensing region SA includes pixels to which pixel data is written, and sensor pixels spaced apart from each other at predetermined intervals with the pixels interposed therebetween. The sensor pixel includes a photosensor and a photosensor driving circuit that drives the photosensor. The display pixels in the second sensing area SA emit light according to the data voltage of the pixel data to display the input data in the display mode, but emit light of high brightness according to the voltage of the light source driving data, and thus are driven as the light source in the fingerprint recognition mode.

In this way, different gamma compensation voltages according to resolutions according to embodiments of the present disclosure may be applied even to a display device to which both the imaging element module and the fingerprint recognition module are applied.

Although the embodiments of the present disclosure have been described in more detail with reference to the accompanying drawings, the present disclosure is not limited thereto, and may be embodied in many different forms without departing from the technical concept of the present disclosure. Accordingly, the embodiments disclosed in the present disclosure are provided for illustrative purposes only, and are not intended to limit the technical concept of the present disclosure. The scope of the technical idea of the present disclosure is not limited thereto. Therefore, it should be understood that the above-described embodiments are illustrative in all respects and do not limit the disclosure. The scope of the present disclosure should be construed based on the appended claims, and all technical concepts within the equivalent scope thereof should be construed as falling within the scope of the present disclosure.

Claims

1. A display device, comprising:

a first data line group including first data lines connected to pixels arranged at a first resolution in a first region of a screen;

a second data line group including second data lines connected to pixels arranged at the first resolution and pixels arranged at a second resolution lower than the first resolution in a second region of the screen;

a first gamma compensation voltage generating unit dividing a first reference voltage and outputting a first gamma compensation voltage;

a second gamma compensation voltage generating unit dividing a second reference voltage and outputting second gamma compensation voltages different according to respective resolutions;

a first data driving unit converting first pixel data to be written in the pixels of the first region into the first gamma compensation voltage output from the first gamma compensation voltage generating unit and outputting a first data voltage to the first data line of the first data line group; and

a second data driving unit converting second pixel data to be written in the pixels of the second region into the second gamma compensation voltage output from the second gamma compensation voltage generating unit and outputting a second data voltage to the second data line of the second data line group.

2. The display device according to claim 1, wherein the second gamma compensation voltage generating unit divides a first voltage level of the second reference voltage and outputs the second gamma compensation voltage during scanning of the pixels arranged at the first resolution in the second region, and divides a second voltage level of the second reference voltage and outputs the second gamma compensation voltage during scanning of the pixels arranged at the second resolution in the second region.

3. The display device according to claim 2, wherein the second reference voltage in a boundary region between the pixels arranged at the first resolution and the pixels arranged at the second resolution in the second region is varied.

4. The display device according to claim 3, wherein the boundary region includes pixels adjacent to the pixels arranged at the second resolution among the pixels arranged at the first resolution.

5. The display device according to claim 3, wherein the boundary region includes pixels adjacent to the pixels arranged at the first resolution among the pixels arranged at the second resolution.

6. The display device according to claim 3, wherein the boundary region includes pixels adjacent to each other of the pixels arranged at the first resolution and the pixels arranged at the second resolution.

7. The display device according to claim 1, wherein each channel of the first data driving unit includes a first digital-to-analog converter converting the first pixel data into the first gamma compensation voltage output from the first gamma compensation voltage generating unit and outputting the first data voltage, and a first output buffer connected to an output node of the first digital-to-analog converter, and

each channel of the second data driving unit includes a second analog-to-digital converter converting the second pixel data into the second gamma compensation voltage output from the second gamma compensation voltage generating unit and outputting the second data voltage, and a second output buffer connected to an output node of the second analog-to-digital converter.

8. The display device according to claim 2, further comprising:

a power supply unit that supplies the first reference voltage and the second reference voltage; and

a timing controller generating a reference voltage control signal for controlling the second reference voltage having the first voltage level or the second voltage level to be supplied to the second gamma compensation voltage generating unit and supplying the reference voltage control signal to the power supply unit.

9. The display device according to claim 8, wherein the timing controller generates a first reference voltage control signal for supplying the second reference voltage having the first voltage level when scanning the pixels arranged at the first resolution in the second region, and generates a second reference voltage control signal for supplying the second reference voltage having the second voltage level when scanning the pixels arranged at the second resolution in the second region.

10. The display device according to claim 1, wherein each of the first and second gamma compensation voltage generating units comprises:

a first circuit unit dividing the first reference voltage or the second reference voltage using a voltage divider circuit and selecting a gamma reference voltage including a highest gamma reference voltage and a lowest gamma reference voltage from the divided first reference voltage or second reference voltage;

a second circuit unit dividing the gamma reference voltages and selecting the remaining gamma reference voltages from the divided first reference voltages or the second reference voltages; and

a third circuit unit dividing the gamma reference voltages output from the first and second circuit units and outputting a gamma compensation voltage for a gray scale,

wherein the first circuit unit, the second circuit unit and the third circuit unit are integrated in a driving integrated circuit, i.e., a driving IC.

11. The display device according to claim 1, wherein the first and second gamma compensation voltage generating units comprise:

wherein the third circuit unit is integrated in a driving integrated circuit, i.e., a driving IC.

12. The display device of claim 1, wherein the first region of the pixels arranged at the first resolution comprises the pixels arranged at a first per inch (PPI), and

the second region of the pixels arranged at the second resolution comprises the pixels arranged at a second PPI lower than the first PPI.

13. The display device of claim 1, wherein the second region in which the pixels are arranged at the second resolution comprises at least one of: the area that includes the pixel and camera module and the area that includes the pixel and fingerprint identification module.

14. An electronic device, comprising:

a first data driving unit converting first pixel data to be written in the pixels of the first region into the gamma compensation voltages output from the first gamma compensation voltage generating unit and outputting first data voltages to the first data lines of the first data line group; and